The present invention is directed generally to a blower assembly suitable for use with a pneumatic transmission system. Specifically, this invention relates to a blower assembly which includes a blower motor and a bypass path. The bypass path provides an alternate route through the blower assembly, so that air may flow through the bypass path rather than the blower motor for reduced path resistance and therefore improved overall efficiency. In one aspect, the invention relates to a pneumatic transmission system with a blower unit having a blower motor and a bypass path.
Blower assemblies where air flow can be selectively directed in either direction are commonly used in pneumatic transmission systems, which are widely known and are used to transmit articles from a first point to a second point, which is remote from the first point. Pneumatic transmission systems usually include at least two stations, a tube or conduit extending between the two stations, and a carrier which can be positioned within the tube so that it can be transmitted from one station to another.
A common example of a pneumatic transmission system is in drive-in bank teller facilities where business is conducted via a carrier transmitted between the bank and the remote drive-in terminal. Other examples include pneumatic transmission systems used for sending documents between different floors in a building or between offices which are located some distance apart.
Typical blower assemblies include two opposing blowers for selectively providing air-flow in opposite directions in the tube or conduit connecting the two stations. FIG. 1 shows an example of a pneumatic transmission system having this type of a conventional blower assembly. The blower assembly 10 includes a pair of vacuum cleaner blower motors 15A and 15B positioned in a blower tube 20 in pneumatic series with each other, meaning the vacuum cleaner blower motors 15A and 15B are within the same air flow path. Furthermore, the vacuum cleaner blower motors 15A and 15B are spatially separated from each other within the blower tube 20. The blower tube 20 and the vacuum cleaner blower motors 15A and 15B are disposed within a blower housing 25. The blower tube 20 is substantially open on one end and closed on the other end except for communication with a vent/inlet 30, which is for supplying or exhausting air. The blower assembly 10 communicates with a transport tube 35 via a conduit 40. The conduit 40 is attached at one end to the blower housing 25 and at its other end to a check/relief valve 45. The check/relief valve 45 controls air-flow between the conduit 40 and the transport tube 35 such that air may flow between the transport tube 35 and the conduit 40 or, alternately, air may flow between the conduit 40 and a second conduit 50. The second conduit 50 is connected at one end to the check/relief valve 45 and at its other end to a station 55. The transport tube 35 is connected to the station 55 at one end and to a second station 60 at its other end, and is of sufficient internal diameter such that a carrier 65 can be transmitted therethrough.
During normal operation, either the first blower motor 15A or the second blower motor 15B is activated based on a desired direction of travel for the carrier 65 through the transport tube 35. In a case where the first blower motor 15A is activated, air is pulled into the blower tube 20 through the vent/inlet 30 and pushed out of the blower tube 20 through the second blower motor 15B, then through the blower housing 25, the conduit 40, the check/relief valve 45, and the second conduit 50 to the station 55. In a case where the second blower motor 15B is activated, air is pushed out of the blower tube 20 through the first blower motor 15A to the vent/inlet 30, and pulled into the blower tube 20 through the blower housing 25, the conduit 40, and the check/relief valve 45 from the transport tube 35.
One disadvantage of a pneumatic transmission system that includes a conventional blower assembly having opposing blower motors is that since the path of air-flow includes a non-activated blower motor, a path resistance of the pneumatic transmission system is increased. Thus, an additional amount of force is required for the air to travel through the pneumatic transmission system due to the path resistance encountered at the non-activated blower motor, reducing the distance a given blower motor can cause a driven member such as a carrier to travel. This additional amount of force also results in an increased amount of work for the activated blower motor over time, which decreases the efficiency of the pneumatic transmission system. Such inefficiency can result in an increase in the cost of operation as well as increased wear on the blower motors. For the foregoing reasons, there is a need for a pneumatic transmission system that has a reduced path resistance for air flow and can therefore operate more efficiently and with an increased transmission range.
An object of the present invention is to provide a blower assembly suitable for use with a pneumatic transmission system wherein the blower assembly provides a path having a reduced path resistance for air flow.
Another object of the present invention is to provide a pneumatic transmission system having an increased range over which a carrier may be transmitted and an improved operating efficiency by reducing the pneumatic resistance of the system.
A pneumatic transmission system having features of the present invention comprises at least a first and a second station, each for sending or receiving a carrier, a transport conduit connected between the first station and the second station, wherein the transport conduit permits a transfer of the carrier between the first station and the second station, and a blower assembly. In one embodiment of the invention, the blower assembly comprises a housing and a blower, a bypass path, and a bypass valve all disposed within the housing. The housing is connected to the first station such that air can flow between the housing and the first station. The blower has an inlet/outlet opening which can serve as both an air inlet for providing air from the atmosphere through the housing to the pneumatic transmission system and an air vent for exhausting the air from the pneumatic transmission system through the housing to the atmosphere. The blower is for moving a volume of the air through the transport conduit. The bypass path provides a path through which air can flow without flowing through the first blower. The bypass valve is for blocking the flow of the air through the bypass path when the blower is active.
In another embodiment of the invention, a pneumatic transmission system is provided comprising a first station and a second station, both for sending or receiving a carrier, a transport conduit connected between the first station and the second station for permitting a transfer of a carrier between the first station and the second station, and a blower assembly. The blower assembly includes a housing and a first interior wall, a first blower, a second interior wall, a second blower, and a valve assembly all disposed within the housing. The housing is connected to the first station such that air can flow between the housing and the first station. Also, the housing has an inlet/outlet opening which can serve as an air inlet for providing air from atmosphere through the housing to the pneumatic transmission system and can serve as an air outlet for exhausting air from the pneumatic transmission system through the housing to the atmosphere. The first interior wall has a blower aperture and a bypass aperture. The first blower is mounted through the blower aperture of the first interior wall, while the bypass aperture of the first interior wall provides a path through which the air can flow without flowing through the first blower. The second interior wall has a blower aperture and a bypass aperture. The second blower is mounted through the blower aperture of the second interior wall, while the bypass aperture of the second interior wall provides a path through which the air can flow without flowing through the second blower. The first blower is for moving a volume of air through the transport conduit in a first direction, whereas the second blower is for moving a volume of the air through the transport conduit in a second direction. The valve assembly operates to allow air to pass through the bypass aperture of the second interior wall while the first blower motor is operating and operates to allow air to pass through the bypass aperture of the first interior wall while the second blower motor is operating.
A bypass valve suitable for use in a blower assembly having features of the present invention may include a valve guide, a valve rod slidably engaged with the valve guide, and a blocking member attached to an end portion of the valve rod. Such a bypass valve may be constructed such that the valve rod is capable of sliding with respect to the valve guide in a direction to block the flow of air through a bypass path with the blocking member, and in a second direction to allow the flow of air through the bypass path. If a second bypass path is present, a second blocking member may be attached to a second end portion of the valve rod. In this case, the bypass valve may be constructed such that the valve rod is capable of sliding with respect to the valve guide in a direction to block the flow of air through a bypass path with the blocking member while allowing the flow of air through the second bypass path, and in a second direction to allow the flow of air through the bypass path while blocking the flow of air through the second bypass path with the second blocking member.
Alternately, a bypass valve suitable for use in a blower assembly having features of the present invention may be an electromechanically operating valve which operates based on a control signal to selectively block or allow air to pass through one or more bypass paths.
Finally, the present invention can be implemented in a pneumatic transmission system having a plurality of stations.